title: Clinical management of small (6- to 9-mm) polyps detected at screening CT colonography: a cost-effectiveness analysis.
abstract: OBJECTIVE
  The primary aim of this model analysis was to compare the clinical and economic impacts of immediate polypectomy versus 3-year CT colonography (CTC) surveillance for small (6- to 9-mm) polyps detected at CTC screening.
  
  
  METHODS
  A decision analysis model was constructed incorporating the expected advanced neoplasia prevalence, frequency of measurable growth, colorectal cancer (CRC) prevalence and risk, CTC performance, and costs related to CRC screening and treatment. CRC risk was assumed to be independent of advanced adenoma size, which intentionally overestimates the risk related to small polyps. Clinical effectiveness and costs for 3-year CTC surveillance versus immediate colonoscopic polypectomy were compared for a concentrated cohort of patients with 6- to 9-mm polyps. For the CTC surveillance strategy, only cases with measurable growth (> or = 1 mm) at follow-up CTC were referred for polypectomy.
  
  
  RESULTS
  Without any intervention, the estimated 5-year CRC death rate from 6- to 9-mm polyps in this concentrated cohort was 0.08%, which is a sevenfold decrease over the 0.56% CRC risk for the general unselected screening population. The death rate was further reduced to 0.03% with the CTC surveillance strategy and to 0.02% with immediate colonoscopy referral. However, for each additional cancer-related death prevented with immediate polypectomy versus CTC follow-up, 9,977 colonoscopy referrals would be needed, resulting in 10 additional perforations and an incremental cost-effectiveness ratio of $372,853.
  
  
  CONCLUSIONS
  For patients with small (6- to 9-mm) polyps detected at CTC screening, the exclusion of large polyps (> or = 10 mm) already confers a very low risk of CRC. The high costs, additional complications, and relatively low incremental yield associated with immediate polypectomy of 6- to 9-mm polyps support the practice of 3-year CTC surveillance, which allows for selective noninvasive identification of small polyps at risk.
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Science Center, 600 Highland Ave., Madison, WI 53792-3252, USA. ppickhardt2@uwhealth.org
authors.forename: Perry J
authors.initials: PJ
authors.lastname: Pickhardt
authors.forename: Cesare
authors.initials: C
authors.lastname: Hassan
authors.forename: Andrea
authors.initials: A
authors.lastname: Laghi
authors.forename: Angelo
authors.initials: A
authors.lastname: Zullo
authors.forename: David H
authors.initials: DH
authors.lastname: Kim
authors.forename: Franco
authors.initials: F
authors.lastname: Iafrate
authors.forename: Sergio
authors.initials: S
authors.lastname: Morini
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D023881:Colonography, Computed Tomographic / Q000191:economics* / Q000706:statistics & numerical data; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging / Q000191:economics / Q000401:mortality / Q000517:prevention & control; D003362:Cost-Benefit Analysis; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007417:Intestinal Polyps / Q000000981:diagnostic imaging / Q000191:economics / Q000401:mortality / Q000601:surgery; D008297:Male; D008403:Mass Screening / Q000191:economics* / Q000706:statistics & numerical data; D008875:Middle Aged; D012189:Retrospective Studies; D016019:Survival Analysis; D015996:Survival Rate; D014481:United States / Q000453:epidemiology